Arc lamp



Nov. 10, 1936. E. c. RICHARDSON ARC'LAMP 2 Sheets-Sheet Filed Aug. 31, 1935 mzagzmm" Nov. 10, 1936. E. c. RICHARDSON 2,060,347

ARC'LAMP Filed Aug. 51, 1935 2 Sheets-Sheet 2 INVENTOR.

W '1 @MCW' 80k ATTORNEYS Patented Nov. 10, 1936 UNITED STATES PATENTOFFICE ARC LAMP Application August 31, 1935, Serial No. 38,749

8 Claims.

This invention relates to are lamps and has particular reference to aconstruction for continuously feeding the positive carbon man are lampemploying a rotating positive carbon electrode.

In certain industries, particularly the motion picture industry, it isnecessary to produce light of high intensity which must be maintained ofsubstantially unvaryingintensity and at a closely. controlled spectraldistribution during the taking of a picture, and particularly inphotographing for production of colored motion pictures. For thispurpose it is common practice to employ a carbon arc lamp of thecharacter in which one of the electrodes, usually the positive, ishorizontally mounted and adapted to be rotated about its longitudinalaxis during the operation of the lamp. Employing a rotating carbon ofthis character, considerable difficulty is encountered in continuouslyfeeding the carbon forward- 1y as it is burned away at its tip since therate of forward motion of the carbon must be extremely small.

It has been discovered that for best results in motion picture lighting,the positive carbon electrode should be rotated at a steady rate ofspeed which is sufficient to maintain a symmetrically formed crater inthe positive carbon as is well known in the art. The problem ofcoordinating such rate of rotation with the much slower rate of forwardfeed of the carbon has presented considerable difficulty due to thelimitations of the gearing employed between the rotating mechanism andthe mechanism employed for feeding the carbon and it has beenparticularly difficult to design into such an arc lamp a means forrapidly adjusting the position of the positive carbon manually as isoften required when carbon electrodes are being replaced for operation.

It is therefore an object of my invention to provide an arc lamp of thecharacter described wherein an axially, horizontally mounted positivecarbon may be readily rotated about its longitudinal axis at acomparatively slow speed and in which mechanism is employed between thedevices employed for feeding the carbon forwardly which will produce apositiva'steady, slow, non-intermittent forward feeding of the carbon inaccordance with the rate at which the tip of the carbon is burned awayin use.

Another object of my invention is to provide gearing between therotating means for rotating the positive-; electrode in an arc lamparound its longitudinalaids, and the feeding mechanism employed forfeeding the positive carbon, which includes a spiral or scroll type ofgear operating upon one or more spur gears, which spur gears engage thecarbon electrode to feed the same forwardly in a non-intermittentmanner.

Another object of my invention is to provide a feeding device forrotating carbon arc lamps in which the carbon is gripped between a pairof spur gears mounted on diametrically opposite sides of the carbon andin which the same spur gears engage a scroll or spiral gear mounted to 1be rotated about the longitudinal axis of the positive rotatingelectrode at a speed different from the speed of rotationof the rotatingelectrode.

Another object-of my invention is to provide 5 an arc lamp structure foruse with a rotating carbon of the character set forth in the precedingparagraphs wherein the change speed gear ling interposed between themechanism for rotating the carbon and the scroll gear is adapted to bemanually manipulated to manually adjust the positive of the carbonwithout disconnecting or interfering with the normal positive carbonrotating system mechanism.

Another object of my invention is to provide a system for rotating thepositive carbon electrode and for feeding said electrode forward as itis consumed in the are at a continuous nonintermittent rate of speed andto provide a means for manually adjusting the position of said rotatingcarbon electrode without interruptingthe continuity of rotation of thepositive carbon electrode, all of said functions being performed in amechanically functioning device (as opposed to electromagnetic control).r'

Other objects of my invention will be apparent from a study of thefollowing specification read in connection with the accompanyingdrawings, wherein Fig. 1 is a side elevational view shown partly insection of an electrode holding and feeding assembly constructed inaccordance with my in vention;

Fig. 2 is a detail sectional view the line II-II of Fig. i;

Fig. 3 is a detail horizontal sectional view taken along line III-III ofFig. 1;

Fig. 4 is a rear end view of the electrode holding and feeding mechanismillustrated in Fig. 1; and

Fig. 5 is a detail sectional view taken along 0 line V-V of Fig. 3,

Referring to the drawings, I have illustrated an electrode mountingconsisting essentially of a suitable base i, to the underneath surfaceof taken along lil which may be attached a driving motor 2, the motorbeing secured to the plate I in any suitable manner as by means of bolts3.

Rising from the base I is a positive electrode support consisting of abearing bracket 4, to which is secured a positive electrode head 6. Byreferring particularly to Fig. 3, it will be observed that the electrodehead 5 has a pair of horizontally extending openings 6 and I, theopening 6 receiving the electrode supporting sleeve or carrier 8,through which the positive carbon electrode 9 projects. The sleeve 8 ismounted in the opening 6 for rotation therein, as by means of a pair ofball bearings i8 and H frictionally held within the interior of theopening 6. The bearings l and II are spaced apart longitudinally of theopening 6 by means of a spacer l2 secured in place in the head by meansof a set screw 13.

The rear end of the electrode sleeve 8 is provided with a beveled gearl4 meshing with a beveled gear secured upon the upper end of a driveshaft I6, which is in turn connected as by means of an insulatingcoupling H, the shaft l8 extending th.ough vertically aligned bearingsin the bracket 4, the lower end of the shaft I8 being connected as bymeans of gears l6 and 28 to a shaft 2| driven by the motor 2.

Thus during the entire operation of the motor 2 the electrode sleeve 8will be rotated to thereby rotate the positive carbon electrode 8. Therotary movement of the sleeve 8 is transmitted to the electrode 8 bymeans of a flange 22 formed upon the forward end of the sleeve 8, thisflange having a pair of radially extending recesses 23 and 24 ondiametrically opposite sides of the electrode 9, in which slots orrecesses operate a plurality of spur 'gear assemblies 26 and 26. Each ofthe spur gear assemblies 26 and 26 is preferably formed as a pair ofrelatively thin disc-like members 26a and 252) preferably formedintegrally with an under-cut peripheral slot 26c separatin the teeth ofthe gear to thereby form in effect a pair of relatively thin spaced spurgears, the teeth of which willengage and grip the electrode at spacedpoints. By mounting the spur gear assemblies'26 and 26 on diametricallyopposite sides of the electrode 9, it will be apparent that fourdistinct points of contact between the spur gears and the electrode areachieved.

The extreme outer end of the sleeve 8 is provided with a forwardlyprojecting wing member 21, which member is provided with a pair ofradially extending slots 28 and 23, in which are slidably supported apair of pin shafts 38 and 3|. The

r pin shaft 38 constitutes the bearing upon which the gear assembly 26is supported while the shaft 3| performs a similar function for the gearassembly 26. By interconnecting the outer ends of the pin shafts 36 and3| by means of relatively light springs 32 and 33, the spur gearassemblies are yieldingly urged into gripping relation with theelectrode 9. is transmitted through the spur gear assemblies and 26acting as a clutch or grip on the electrode 9.

The forward and rearward movement of the electrode 9 within the sleeve 8is controlled by rotating the spur gear assemblies 25 and 26 about theirpin shafts and 3!. This is accomplished by mounting a disc-like gearmember 34 upon the exterior of the sleeve 8 so as, to be rotatablerelative to the sleeve 8. I prefer to form a hear ing surface 35 on thesleeve 8 by slightly enlarg ing the diameter of the sleeve 8 immediatelyat the rear of the flange 22.

Thus rotation of the sleeve 8 The disc-like gear 34 is provided upon itsforward face with spiral or scroll gear teeth 36 adapted to engage theteeth of the spur gear assemblies 26 and 26. Thus if the scroll gearmember 34 is rotated about the longitudinal axis of the electrode 8 atany speed different from the speed of rotation of the sleeve 8, therelative motion between the spur gears 26 and 26 and the scroll gear 34will cause the spur gears 26 and 26 to rotate about their pin shafts tomove the electrode 9 forwardly or rearwardly, depending upon the ratioof such speed difference.

In order to insure the steady intensity of the light produced from anarc lamp, the positive .carbon should be fed into the arc continuouslvat a rate of speed equal to the speed at which the extreme end of thecarbon is burned away. If the forward feeding of the carbon 8 isintermittent, there will be a considerable fluctuation in the arc and aconsiderable variation in the in tensityof the arc immediately beforeand immediately after the forward feeding movement is accomplished.However, if the carbon 3 is fed forwardly with a steady and continuousnonintermittent motion at the proper rate of speed, the arc will burnsteadily with a relatively unvarying intensity. It is this lattercondition which is most desirable in photographic work since anyvariation in intensity of the light upon the object will cause thephotographic film to register images of varying density, producing anunsatisfactory result.

With the construction hereinbefore described. a steady forward feedingof the electrode 9 may be readily accomplished by rotating the scrollgear 34 at the proper difference in speed relative to the speed ofrotation of the electrode 8 about its axis.

The driving motion for the scroll gear 34 may be readily transmittedthereto from the same.

driving force which rotates the carbon 9, as by mounting a secondarysleeve 31 for rotation in the second opening I on the head 6. The sleeve31 may be mounted upon suitable spaced ball bearings 38 and 38 inparallel relation with the sleeve 8. The forward end of the sleeve 31extends radially as a flange 40, upon the periphery of which are cut.spur gear teeth 4| adapted to mesh with a spur gear 42 fixedly mountedupon the sleeve 8, as by means of a keyway 43 formed in the gear 42,engageable with an outwardly projecting pin 44 secured to the sleeve 8.The flange has its forward surface engaged with the rear surface 46 of asmall gear 46 so as to cause the gear 46 to be frictionally coupled tothe flange 48. The gear 46 is rigidly secured as at 41 to a rearwardlyextending shaft 48 having a shoulder or collar 49 formed thereon servingas an abutment for a spring 50, the opposite end of which engages therear face of the clamping nut 6| held in place by a set screw 5m andretaining the assembly mounted on sleeve 31 so as to exert a continuousrearward pressure upon the gear 46 to insure frictional engagementbetween the gear 46 and the flange 40.

The gear 46 is meshed with spur gear teeth 62 on the periphery of thescroll gear 34 so that rotation of gear 42 by the sleeve 8 will betransmitted through the flange 40 and gear 46 to the scroll gear 34. Byselecting the diameters of the gear 42, the flange 40, the gear 46 andthe scroll gear 34, any desired ratio of speed may be obtained betweenthe speed of rotation of the sleeve select the gear ratios such as tocause the scroll gear 34 to rotate at a slightly lesser speed than thesleeve 8, thus using the differential between the two speeds to achievethe forward driving movement of the spur gears 25 and 26 though it willbe understood by those skilled in the art that by arranging the gear 35to rotate at an increased speed over that of the sleeve 8, the sameeffect may be accomplished by changing the direction of the spiral teeth36 on the scroll gear 34.

By employing the friction coupling between the flange fill and the gear46, it will be apparent that the scroll gear 35 may be rotated in onedirectionor the other independent of the movemerit of the sleeve ii toachieve the initial adjustment of the electrode 9 or to make rapidadjustments in the position of the electrode 9 if and when such may bedesired. The shaft ill may be coupled, as indicated at Gil, to a manualshaft 6i extending to any desired position and provided with anysuitable handle, not shown, by which the gear 35 may be manuallyrotated, and the positive rotating carbon fed forward or backward asdesired while the rotation 01 the same is undisturbed by the manualadjustment during operation.

. As will be understood by those skilled in the art, various parts ofthe mechanism are insulated from each other in the manner well known inthis so as to isolate the various components from ch other with respectto the currents carried .z-ls is usually desired in arc lamps of thischaracter, the negative electrode ill may be continuously andautomatically fed toward the positive electrode ii as the negativeelectrode is burned away by mounting the negative electrode in asuitable carriage which is in turn mounted upon a threaded shaftjournaled upon a nega tive electrode head The shaft as is preferablyslidably mounted, as well as rotatably mounted, in its bearings and sothat a rapid upward movement of the negative electrode may beaccomplished by a bell cranir llil pivpen the head as indicated at andig a collar on the threaded shaft til.

movement or the bell. cranlr above its Jill lift the entire shaft litand the carriage to move the electrode into engagement wi .1 theprojecting end of the electrode 9 whenever is desired to strike the arc.

The shaft may be provided with a bevel gear ll mesh d with a bevel gearit connected to a shalt l3 whichis in tu n geared as indicated at it toa worm wheel driven by a worm on the main drive shaft the worm wheel llbeing irictionally or mechanically or by means of a throw out clutchcoupled as indicated at ill to the l, permitting manual movement of theshaft independent of the drive shaft ill through agency of an adjustingshaft whenever such adjustment is desired.

Again will be understood by those slr'lled in the art that whileillustration and description or the electrical circuits leading to theelectrodes has omitted herein, the usable circuit arrangement supplyingcurrent to the two eiectrodes with a ballast resistance interposed therin may be employed and that the motor will be connected in shuntrelation to the electrodes in suchmanner that the motor will operate ata speed corresponding to the voltage across the are, thereby achievingthe feeding of the carbon in vided an arc lamp inwhich the positivecarbon may be mounted horizontally and may be rotated at any desiredspeed best adapted for maintaining the most effective crater conditionin electrode 9 for the most advantageous production of light and theproduction of the particular light values desired, while the rotarymotion of the carbon is employed for longitudinally feeding the carbonat a rate proportional to the rate at which the carbon is consumed,which longitudinal feeding will m steady, even and continuous during theentire operation of the lamp and which permits the necessary manualadjustments of the carbon position without interfering with thelongitudinal feeding thereof.

While I have shown and described the preferred embodiment of myinvention, I do not desire to be limited to any of the details listedand described herein except as defined in the appended claims.

I claim: 1. In an arc lamp, an electrode, a rotatable electrode carrierfor carrying said electrode for rotation about its longitudinal axis,electrode feeding means engaging said electrodenieans mounting saidfeeding means on said carrier for rotation in the direction oi thelongitudinal axis oi said electrode axis, a scroll gear rotatable onsaid electrode carrier and meshed with said feeding means, and gearmeans interposed between said carrier and said scroll gear tocontinuously and non-intermittently rotate said scroll gear by rotationof said carrier but at a chflerent from that ol said carrier,

2. in an arc lamp, a positive electrode, a nega tive electrode, arotatable carrier means mounting said positive electrode for rotationabout its lon gitudinal aids relative to the negative electrode, meansfor longitudinally moving said positive electrode including rotatableelectrode engaging means, means mounting said engaging means forrotation the direction of the longitudinal axis of electrode, scrollgear associated with said electrode engaging means for rotating thesame, means interposed between said scroll and said carrier means forcontinuously coupling said scroll gear to said carrier meansnominterrnittently for rota g sa scroll a diile'rent rate or: speec ofsaid electrode mounting means.

3. in an arc lamp, a pair of electrodes, a rotat able sleeve throughwhich one oi said electrodes projects, a pair of gear members carried bysaid sleeve, means mounting said members for rctation in the directionof the longitudinal axis of said electrode, scroll gear rotatable aboutsaid sleeve meshed with said gear members, and gear meanshiterconnecting scroll gear with said sleeve for continuous,noninteririttent rotation a speed different from the speed of rotat onoi sail sleeve.

an lamp, a pair of electrodes, a rotatable sleeve through which one ofsaid electrodes projects, plurality oi members carried by sleeve onradially opposed sides oi said elec trade for enga ing said electrode tofeed the same, means mounting said gear membersior rotation in thedirection of the longitudinal axis of said electrode, a scroll gearrotatabl mounted upon sleeve and meshed with said gear means, means forrotating said sleeve, and gearing interposed between said sleeve andsaid scroll gear to continuously and non-intermittently rotate saidscroll gear at a speed different from the speed of rotation of saidsleeve.

5. In an arc lamp, a pair of electrodes, a rotatable sleeve throughwhich one of said electrodes projects, a pair of gear members carried bysaid sleeve on diametrically opposite sides of said electrode forengaging said electrode to feed the same, means mounting said gearmembers for rotation in the direction or the longitudinal axis 0! saidelectrode, a scroll gear rotatably mounted upon said sleeve and meshedwith said gear means, means for rotating said sleeve, 8. gear rigid withsaid sleeve, a shaft parallel with said sleeve having a gear meshed withsaid sleeve gear, and a second gear on said shaft for continuouslynon-intermittently driving said scroll gear at a speed differing fromthe speed of rotation of said sleeve.

6. In an arc lamp, a pair of electrodes, a rotat able sleeve throughwhich one of said electrodes projects, a pair of gear members carried bysaid sleeve on diametrically opposite sides of said electrode forengaging said electrode, means mounting said gear means for rotation inthe direction of the longitudinal axis of said electrode, a spur [earhaving a scroll gear on one of its faces, means mounting said scrollgear on said sleeve for rotation relative thereto, a gear flxed to saidsleeve, and gearing interposed between said flxed gear and said scrollgear for continuously and non-intermittently rotating said scroll gearby rotation of said sleeve at a speed differing from the speed of saidsleeve.

'7. In an arc lamp, a pair of electrodes, a rotatable sleeve throughwhich one of said electrodes projects, an end flange on said sleeveextending radially at one end thereof, a pair oi gear members forengaging said electrode, means mounting I said gear members on the endflange of said sleeve for rotation in the direction of the longitudinalaxis of said electrode, a scroll gear rotatably carried by said sleeveimmediately to the rear of said flange and meshed with said gear means,and means interposed between said scroll gear and said sleeve forcontinuously and nonintermittently rotating said scroll gear at a speeddiflering from the speed of said sleeve.

8. In an arc lamp, 0. pair of electrodes, 9. rotatable sleeve throughwhich one of said electrodes projects, an end flange on said sleeveextending radially at one end thereof, a plurality oislots in saidflange disposed about said electrode and extending radially thereoi, aplurality of gear members carried on the front of said flange andextending through the slots, means mounting said gear members on saidflange for rotation in the direction of the longitudinal axis of saidelectrode, a scroll gear rotatably mounted on said sleeve immediately atthe rear of said flange and meshed with said gear members at the rear ofsaid flange, and gearing interposed between said scroll gear and saidsleeve for rotating said scroll gear at a speed differing from the speedof said sleeve.

ELMER C. RICHARDSON.

